The work proposed in this grant has the long term goal of understanding the neural systems which allow us to control movement. Both anatomy and physiology will be used to investigate fundamental questions concerning cerebellar functions. The anatomical studies will make use of recently introduced techniques (transport and demonstration of labeled lectins) which are powerful and efficient for simultaneously tracing input and output connections of small areas of the nervous system. Areas of the cerebellum involved in controlling specific limb movements will be defined with more precision than has yet been accomplished. Limb specific portions of the magnocellular red nucleus and interpositus nucleus of cat and monkey will be identified with electrophysiological techniques and injected with HRP labeled wheat germ lectin. In combination with the anatomical studies, the functional properties of the same areas will be determined through the use of chronic single unit recording in behaving monkeys. Recordings will be made while the subjects perform a variety of highly trained motor tasks, and the neural signals will be related to specific parameters of movement. In this way, an understanding of the role the cerebellum plays in normal movements will be gained. Basic questions such as whether the cerebellum is acting in error correction or initital motor programming and with what sort of "language" does it carry out its motor functions will be answered. The information gained will be valuable in the study, diagnosis and treatment of pathological states affecting movement. Recent advances in biotechnology have led researchers to attempt to mimic neural motor control for prosthetic purposes. Understanding the neural signals involved in motor control is a prerequisite for guiding and evaluating the feasibility of various clinical approaches.